Terrain Awareness and Warning Systems (TAWS) for aircraft such as fixed wing and rotary wing vehicles have significantly contributed to the safety of flight. Briefly, and in general terms, the TAWS is operable to acquire selected flight-related information from various aircraft systems and to obtain terrain information for topological features surrounding the aircraft. The TAWS is configured to process the flight-related information and the terrain information to determine if a potential safety condition due to terrain proximity is present. If a terrain proximity hazard is determined to exist, the TAWS provides a flight crew with a suitable audible and/or visual warning that timely alerts the flight crew regarding the detected terrain hazard.
Although TAWS are generally effective in enhancing the safety of flight, drawbacks nevertheless exist. For example, in certain geographical locations, the aircraft may be intentionally operated relatively close to the surrounding terrain so that numerous terrain proximity messages are generated by the TAWS and communicated to the flight crew. In such cases, the flight crew is generally capable of maintaining sufficient visual contact with the surrounding terrain so that the aircraft may be safely navigated along a desired flight path without assistance from the TAWS. Accordingly, the numerous terrain proximity messages may constitute a nuisance that may distract the flight crew from other important flight-related tasks. Thus, in order to eliminate the undesired, or “nuisance” terrain warnings, the flight crew may deactivate the TAWS so that the nuisance messages are suppressed. An obvious shortcoming associated with deactivation of the TAWS is that an undesired terrain incursion may nevertheless occur during a temporary period of flight crew inattention to the visual monitoring of surrounding terrain.
It would therefore be desirable to provide systems and methods that permit the ground proximity messages to be selectively suppressed by the flight crew to eliminate “nuisance” messages, while desirably maintaining the considerable flight safety aspects of TAWS.